A Dual-Mode Terahertz Filter Based on a Metallic Resonator Design

We present a metallic resonator fabricated on silicon capable of dual-mode operation at terahertz frequencies. The resonator exhibits a notch plus stop band filter response or a notch filter response depending on the orientation of the incident electric field with respect to the structure. The former results in two resonance features: one at 0.69 THz with a Q-factor of 3.7 and the other at 0.91 THz. The latter results in a resonance feature at 0.63 THz with a Q-factor of 5.7. Using 3D finite-difference time-domain simulations, the resonator is designed to operate between 0.1 and 1.4 THz. Experimental verification is performed using a free space terahertz time-domain spectroscopy system, and agreement with our simulations is realized.